MOUNT MERAPI, Indonesia — Two men who sought shelter from an erupting volcano in an underground bunker were found dead from burns Friday, officials said.

The men fled to the steel shelter on Wednesday while evacuating villagers during a burst of volcanic activity on Mount Merapi, and the bunker was later covered with up to 6 feet of debris as hot as 572 degrees Fahrenheit.

Rescuers found the two bodies after opening the steel bunker early Friday, said Widi Sutikono, head of volcano relief operations.

“The bodies were burned because of the hot temperatures in the bunker,” Sutikno said.

Heat melted shovels

The two men, volunteers who were helping evacuate a village, had been trapped since late Wednesday when Mount Merapi sent massive clouds of searing gas and rock fragments rolling far down its slopes. Rescuers made contact with one of the men, but the men's phones stopped working.

On Thursday, fierce heat melted the troops’ shovels and the tires on a mechanical digger brought in to plow through more than six feet of debris covering the bunker, which was built for protection from volcanic eruptions, said Maj. Sunarso, who goes by one name.

By the time digging was suspended Thursday night, soldiers serving as rescuers had moved away the debris surrounding the door, but found it blocked by a large hot boulder.

Continuing eruptionsMerapi continued to spew out scorching gas clouds and rock fragments Thursday, with one black plume in the mid-afternoon covering a large swath of the mountain. No injuries or fresh property damage was reported.

Scientist Antonius Ratdomopurbo said the resurgence in activity was likely caused by the collapse of a section of the volcano’s lava dome, which has been growing in recent weeks as lava emerges from its core.

Merapi is one of more than 70 active volcanoes in Indonesia.

The main dangers at Merapi are fast-moving bursts of blistering gases and rock fragments called pyroclastic flow. Experts say a massive vertical eruption threatening people many miles away will not occur.

One killed more than 60 villagers in 1994, and about 1,300 people died when Merapi erupted in 1930.